The carding operation is conventionally performed by means of one or more rotating circular tools in the form of brushes with metal bristles or cards from which is derived the name of carder for the machine designed for this work.
Known carding machines are structured in such a manner as to complete the carding through the movement of a carriage on which is arranged the back of the footwear and the tool-holder arm is provided with a brush which moves transversely or along a direction forming a certain angle to the axis of travel of said carriage.
In some embodiments there is provided another tool-holding unit with associated brush, generally fixed, designed to remove excess glue and unsightly ripples in the upper present in particular opposite the toe and heel.
Such carding machines have various shortcomings due mainly to the need for moving two members, i.e. the carriage which carries the upper and the tool-holding arm which carries the brush.
Movement of the two members leads to considerable construction complexity of the carding machine.